1. Field of the Disclosure
The present disclosure generally relates to signal noise reduction, and more particularly to decision feedback equalization.
2. Description of the Related Art
In a serial communication system, such as a graphics processing unit (GPU) memory interface, an information signal is transmitted through a medium, received, and processed. The received information signal has typically been degraded by all the media through which it has passed, including the transmitter, the transmission medium, the package, the receiver, and other media. The degradation can result from a variety of noise sources, including intersymbol interference (ISI), cross-talk, transmission reflections, and the like. The degradation in the received information signal can cause difficulty in extracting the transmitted information, putting limitations on the frequency of transmission, the transmission distance, and/or adding to the complexity, area, and power of the receiving circuitry.
There are multiple techniques for correcting, or reducing, the degradation in the received information signal. One such technique is referred to as decision feedback equalization (DFE). When a step or a pulse is transmitted, the effects of the noise sources can last for a short duration or for long periods of time, thereby affecting subsequent steps or pulses. For example, a transmitted pulse (corresponding to a digital value of “1”), may cause noise that interferes with subsequent transmitted data. Thus, a transmitted digital value of “1” can cause a subsequent transmitted digital value of “0” to erroneously appear as a digital value of one in the received signal. A DFE system can cancel or reduce the noise caused by previously transmitted values, thereby improving the accuracy of information retrieved from the received signal.
The use of the same reference symbols in different drawings indicates similar or identical items.